docs: Add missing chat prompt message styles

Author: tjtanjin

docs/api/bot_options.md

@@ -447,6 +447,8 @@ If you wish to make further changes to the chatbot styles, then below is the lis
 | chatInputAreaStyle           | object                          | {}                                                                                       | Styles for the chatbot input container.                                                                                                   |
 | chatInputAreaFocusedStyle           | object                          | {}                                                                                       | Styles for the chatbot input container when it is focused.                                                                                                   |
 | chatInputAreaDisabledStyle           | object                          | {}                                                                                       | Styles for the chatbot input container when it is disabled.                                                                                                   |
+| chatMessagePromptStyle           | object                          | {}                                                                                       | Styles for the new message prompt.                                                                                                   |
+| chatMessagePromptHoveredStyle           | object                          | {}                                                                                       | Styles for the new message prompt when it is hovered.                                                                                                   |
 | chatWindowStyle          | object                          | {}                                                                                       | Styles for the chatbot window.                                                                                                  |
 | footerStyle              | object                          | {}                                                                                       | Styles for the chatbot footer.                                                                                                  |
 | headerStyle              | object                          | {}                                                                                       | Styles for the chatbot header.                                                                                                  |